Process of clarifying liquid silicate of soda or the like.



J. G. VAIL & J. D. CARTER. PROCESS OF OLARIFYING LIQUID SILIOATB 0P SODA 0? THE LIKE.

APPLICATION FILED MAY 1, 1914 Patented Mar. 23, 1915.

I N VE N T OPS James 6. nl', (fa/7]; 6707/72! WITNESSES 4% ATTORNEY ED T ,ENT OFFICE it JAMES VA IL, OF CHESTER, AND JOHN D. CARTER, F LANSDOWNE. PENNSYLVANIA.

PROCESS or QLABIFYING LIQUID SILIGATE or SODA on THE LIKE.

Specification of Letters Patent. t t M 23, 1915.

Application filed May 1, 1914. Serial No. 835,604.

- To all whom it may concern pared generally by the fusion of a suitable sand and soda or potash in a suitable fur nace, is a viscous liquid having a cloudy and opaque appearance. It is also frequently decidedly grayish in color, although it may sometimes have a slightly brownish or even greenish hue, the color seeming to depend upon the nature or quality of the sand or silica employed in the formation of the solid silicate. The discolored, opaque, and cloudy appearance of the liquid silicate is undesirable from a commercial standpoint and limits the use of the article in certain of the arts. It is believed that this discolored and cloudy appearance of the liquid is due to a quantity of extremely finely divided suspended matter mechanically maintained within the liquid, which, owing to the viscosity of the liquid and its own infinitesimal weight, will not entirely settle out even though the liquid be kept standing for long periods of time, and which moreover cannot be readily filtered out or otherwise mechanically removed or chemically precipitated by any method :hitherto known. Numerous attempts to discover a practicable method suitable for commercial use for clarifying liquid silicates have been made, and, while such attempts have met with some degree of success when the liquid is of a comparatively low degree of concentration, as for example, below 15 Baum, and while, by certain careful and painstaking special methods of filtration it has been possible to remove a considerable portion of i the discoloration and cloudy appearance from the more concentrated liquid silicates, as for example those of 40 Baum concentration, yet these latter filtration processes have been by no means satisfactory from a commercial the liquid becomes substantially as clear andbrilliant in appearance as pure water, and when placed in a suitable transparent contamer such as a bottle, cannot by its appearance be easily distinguished therefrom A principal object of our invention is,

therefore, to provide a process for clarify- I ing liquid silicate of soda or the like of a considerable degree of concentration, as for example up to 40 Baum or slightly greater concentration. Further objects of our invention are to provide such a process which shall be capable of being readily carried out, which shall not materially increase the cost of the finished product, which shall require no especial degree of skill on the part of the operator, which shall be thoroughly feasible and practical from a commercial standpoint, which shall not materially affect thedegree of concentration of the silicate treated, and which shall not necessitate the employment of any specificform of apparatus. Our invention further includes all of the other novel features, operations and characgeigstics hereinafter more definitely speci- While we do not desire to limit ourselves to any specific form'of apparatus for carry ing out our process as hereinafter described, as the same may be performed in any suitable apparatus, nevertheless, for the purpose of facilitating the description of our process, one form of apparatus suitable for carrying it out is diagrammatically illus trated in the accompanying drawing forming a part of this specification.

Broadly speaking, our process consists in the treatment of liquid silicate of soda or the like in the presence of heat, in a suitable closed container, and for a suitable period, while maintaining the liquid'in a quiescent state. Such treatment may be conveniently carried out in an apparatus similar to that diagrammatically illustrated inthe accompanying drawing, in Which 1 is a suitable tight receptacle of any desired size, and of sufi'icient strength to withstand considerable internal pressure, provided at its upper end with a pipe 2, having a valve 3, through which the liquid silicate may be introduced within the receptacle. lhe top 4 of the receptacle may be made removable as shown, and a suitable steam coil 5 may be provided in the interior of the receptacle, a pipe 6 provided with a valve 7, being arranged to admit steam to the coil, and another suitable pipe 8 to conduct it from the coil. Preferably at the center of the bottom of the receptacle may be located another pipe 10, having a valve 11, the bottom of the receptacle being preferably somewhat inclined downwardly toward the center. Located a short distance above the bottom may be another pipe 15, provided with a valve 16, and connecting the interior of ready closed. Steam at a suitable pressure is then admitted to the interior of the steam coil 5 for a suitable period, depending upon thedegree of concentration of the silicate and the temperature of.the steam. In

practice for example, good results/may be obtained with silicate of 40 Baum concentration, when the treatment is continued for a period of approximately 'two hours, the steam within the coil being maintained approximately at a pressure-of 75 to 80 pounds. At the end of the period of treatment, it will be found that a considerable quantity of finely divided, 'flocculent matter will havebeen precipitated. to the bottom of the receptacle, and that above this'matter the liquid silicate will be substantially as clear, brilliant and transparent as water, and it may. be drawn off from above the precipitate in any desired manner. We have found in practice, however, that it is. desirable to draw off the liquid silicatewhile heated and still under the pressure generated within the receptacle, which may be readily done ,by means of the pipe 15, and for the purpose of cooling the liquid asit is drawn oil and preventing thesame'from being atomized by the pressure behind it when itreaches a point of lower pressure in the pipe 15, we have found it desirable in practice to provide a cooling coil or similar apparatus 18 of any suitable construction, through which the liquid may be caused to flow and from which it may be led by the leading-o3 .as heretofore stated may be carried out in pipe 25, provided with the valve 26 for controlling the flow of the liquid to any desired receptacle. It will be found that the liquid silicate of soda which flows from this pipe will be substantially transparent in appearance as hitherto described, and'that its degreeof concentration will not have been materially increased owing to the treatment of the silicate having been carried out in a closed-vessel. From time to time after the treatment of a quantity of the liquid silicate, the precipitated matter may be drawn ofi' from the receptacle by the pipe 10, and the interior of the receptacle cleaned out by flushing or in any other desired manner.

In the carrying out of our process we have found that the most satisfactory results are attained with those silicates in the formation of which" silica or sand having a small propbrtion of alumina is utilized." We therefore consider it advisable to supply this element at the time of the formation of the solid silicate in the furnace, or otherwise, if it be not already present in sufficient quantities in the silica or sand. How- "ever, the presence of the alumina seems by no means necessary to the successful operation of the process, and it may therefore be omitted if desired. Moreover, we have further discovered that the presence of magnesia in the sand from which the silicate was made, .or its presence from other causes in the liquid silicate is inimical to the successful working of our process, and the use of sand or other materials containing this element should therefore be avoided.

We do not desire to limit ourselves in the carrying out of our process to any specific form or style of apparatus, as the process any apparatus suitable for the purpose, that form of apparatus diagrammatically illus trated in the drawing being merely one form suitable therefor, nor do we desire to limit ourselves to any specific temperature of any specific length of time duringwhich the liquid silicate is to be treated, as it will be found in practice that both the temperature at which the'liquid silicate is maintained during the process as well as the length of time during which the liquid sili cate is treated may be varied within consid erable limits and still produce satisfactory results, and it will thus be evident that various changes may be made in the details 1% of the process Without departing from the spirit and scope of the invention as defined in the appended claims. Having thus described our invention, We. claim and desire to protect by Letters Pat ent of the United States:

1. The process of clarifying liquid silicate of soda or the like, which comprises the treatment of the liquid silicate with heat while in a quiescent condition.

2. The process of clarifying liquid silicate of soda or the like, which comprises the treatment of the liquid silicate with heat in a closed container without agitation.

3. The process of clarifying liquid silicate of soda or the like which consists in exposing the liquid silicate in a quiescent condition to the action of heat and pressure in a suitable receptacle.

4. Thev process of clarifying liquid silicate of soda or the like which consists in introducing the liquid silicate into a suitable receptacle, exposing the liquid silicate to the action of heat therein without agitation,

and withdrawing the liquid silicate from said receptacle through a cooling coil.

5. The process of clarifying liquid silicate of soda or the like, which consists in able closed receptacle, subjecting the liquid silicate to heat and pressure within said receptacle while said liquid is maintained in a quiescent condition, and withdrawing the silicate from a point above the bottom of ,said receptacle while the pressure. is substantially maintained within said receptacle.

In witness whereof, we, JAMES G. VAiL and JOHN D. CA TER, have hereunto set our hands this 29th day of 4th 1110., A. D. 1914.

JAMES G. VAIL. JOHN D. CARTER.

Witnesses: HENRY W. JoNEs,

CLIFFORD E. BLYTHE. 

